The Neural Prosthesis Program of the National Institute of Neurological Disorders and Stroke is committed to the development of safe, reliable and effective methods for stimulating selected portions of the nervous system. For functional electrical stimulation in spinal cord injured individuals, reliable methods are needed to selectively stimulate paralyzed muscles in a controlled fashion. This research contract is for the development of an implantable microstimulator capable of stimulating paralyzed muscle. The stimulator system will consist of an external transmitter coil and an implanted module that consists of a receiver coil, a stimulator circuit and a pair of stimulating electrodes. The receiver-stimulator electrode implant will be miniaturized to the extent that it can be implanted percutaneously through a hypodermic needle. The implanted receiver-stimulator will also be addressable so that one transmitter coil will be capable of powering and controlling up to 30 implanted receiver-stimulators. The stimulators will be designed to produce stimulus pulse currents at amplitudes and frequencies that are compatible with stimulation of muscles in the forearm.